The conventional level posture sensor contains a solid pendulum style and a liquid pendulum style. The two pendulum styles level posture sensors both have the disadvantages of a complex structure, a bad anti-impact performance and long responding time and so on to a various degree. A one dimension gas pendulum style level posture sensor using “gas pendulum” instead of “solid pendulum” or “liquid pendulum” is provided in the invention whose application number is 93216480.3 filed by the present applicant with the Chinese Patent Office. This level posture sensing element generally utilizes a single-chamber double-fuses structure where there are two thermosensitive fuses in the hermetic chamber through which constant currents flow. The thermosensitive fuses heat the gas in the chamber as a heat source, and at the same time the thermosensitive fuses are also used as measuring elements, the two thermosensitive fuses composing two arms of a signal detecting bridge. When the one dimension gas pendulum style level posture sensing element is in a horizontal state, the hot airflows generated by the two thermosensitive fuses are both in vertical upward directions, both of them are on an identical isotherm, the resistances of the two thermosensitive fuses are the same, the bridge is in balance, and the output voltage of detecting circuit is 0. When the sensing chamber is inclined an angle degree relatively to horizontal surface, the two thermosensitive fuses are on different isotherms separately, the resistances of the thermosensitive elements vary differently, the resistances of the two thermosensitive fuses are unequal, the bridge is out of balance, and a voltage proportional to the inclination angle is output.
However, the one dimension structure level posture sensing element can only sense level posture in one direction. If a two dimension level posture needs to be measured, two sensors amounted vertically must be used such that the volume is much lager than that of the one dimension; meanwhile the cross coupling of the axes is often larger because of the greater difficulty of the vertical amounting. Moreover, the thermosensitive fuses function both as detecting temperature and as heating at the same time. To ensure that the thermosensitive fuses could have sensitivity high enough and chamber temperature, the current flowing in the thermosensitive fuses is generally large, the temperature of the thermosensitive fuses is high, and the detecting performance of the thermosensitive fuses is reduced such that the stability of the sensor becomes poor.
For the purpose of improving performance and reducing cost and decreasing volume, 13th Institute of CETC issues “Research on reliability of the MEMS convective accelerometer” (Micronanoelectronic Technology, 2003, July-August, pages 317-320) wherein a resistance of a fuse is between 300Ω˜1000Ω.
The processes used in “Micromachined Convective Accelerometer” reported by Hebei Semiconductor Research Institute (Chinese Journal of Semiconductors, 2001, Vol. 22, No. 4, pages 465-468) are those: thermally growing a layer of SiO2 on (100) Si, depositing a layer of polysilicon, then photo etching, and boron diffusing the polysilicon to inform resistor strips, and finally depositing a layer of silicon nitride (SiNx) so as to construct a polysilicon thermosensitive resistor and a heat resistor.